 
Philip T. answered  05/06/19
Micro and Macro Economics made simple! Experienced Ivy League Tutor
These are specific terms related to the use of calculus in math.
With a given formula, we can use calculus to derive a number of additional formula and expressions. For example:
From a given cost function, we can take the first order derivative to find the marginal cost
From a given revenue function, we can take the first order derivative to find the marginal revenue
From a given utility function, we can take the first order derivative to find the marginal utility.
Once you have found the derivative of a function, you can in fact take a second derivative (second order condition) which we often undertake to find whether slopes of lines are positive or negative, or whether they are maximums or minimums.
These are just mathematical tools and techniques then to solve economic problems.
 
     
             
                     
                    